Directional radio receiver system



May 10, 1949. w. P. Ll-:AR

DIRECTIONAL RADIO RECEIVER SYSTEM original Filed Nov. 27. 19:59'

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l HWENTQR william 3. Gear ATTORNEY.

Patented May 10, 1949 UNITED STATES PATENT OFFICE DIRECTIONAL RADIORECEIVER SYSTEM William P. Lear, North Hollywood, Calif., assignor, bymesne assignments, to Lear, Incorporated, Grand Rapids, Mich., acorporation of Illinois 16 Claims.

This invention relates to radio guidance receiver systems for mobilecraft, and more particularly to novel radio instrument approach receiversystems for guiding an aircraft to a landing runway, a marine vesselinto a slip, and the like. This case is a division of my copendingapplication Serial No. 306,315 filed November 27, 1939, now Patent No.2,379,363, granted June 26, 1945.

In accordance with my present invention, I provide a radio instrumentapproach receiver system which continuously indicates to the pilot hisrelative lateral position with respect to his destination in general,and his position with respect to the approach path to the destination.Two spaced non-directional transmitters are placed in line with theapproach path. The receiver system is simultaneously tuned to bothtransmitters and has two needle indicators arranged to continuously andindependently point out the direction to each of the transmitters. Thepilot is thus continuously made aware of his position.

In accordance with the present invetnion, the two transmitter stationshave different radio frequencies and continuously radiatenon-directionally. Two rotatable directional antennae aboard theaircraft separately receive the radio signals, and are automaticallycontrolled by a receiver system to maintain a predetermined null signalor bearing position with respect to the transmitters. Two separateautomatic radio direction indicators, one tuned to each of the groundstations, are used with a composite indicator having a separate needlecontinuously controlled by each direction finder.

A common amplifier system is used and continuously operating switchingmeans is arranged between the two tuning units and the common amplifiersystem, successively connecting each tuning unit to the amplier at apredetermined rate to maintain the individual loop antennae andassociated indicators in bearing relationship with correspondingtransmitters. The switching action may be performed mechanically orelectrically.

It is among the objects of the present invention to provide a novellateral position radio indication system comprising two separatedirectional indicators; to provide a novel radio lateral position systemcontinuously effective in apprizing the pilot of his exact relativeposition with respect to transmitter stations; to provide a novel radioguidance system employing two separate radio frequency tuning units anda common amplier and control arrangement; and to provide a novel radioguidance system employing two radio frequency tuning units and a commonamplier and contro1 system therefor with means for effecting successiveconnection between the tuning units of the amplifier.

These and further objects of the present invention will become apparentin the following description of the embodiment shown in the accompanyingdrawing. In the drawing, the single figure illustrates the radioguidance receiver system of the present invention.

The radio guidance receiver system of the present invention is adaptedto operate in the manner described in detail in connection with Fig. 1of my Said Patent No. 2,379,363,

The receiver system schematically illustrated in the drawing is employedin conjunction with ground stations having two separate radio frequencycarrier waves radiating continuously. Separate radio frequency tuningunits are used for both stations and a common amplifier and controlsystem is used for both tuning units. The synchronous switching action,successively connecting the common amplifier-control 'system with theoutput of the radio frequency tuning units, is effected locally in thereceiver. The synchronous switching means may be mechanical orelectronic and is designed to switch the amplifier and contro1 unit atpredetermined intervals of equal duration, preferably in the range ofone-third to one-half of a second, giving bearing indications closelycorresponding with the desired lateral guidance indications.

In the illustrated system, an electromechanical switching means is used,comprising continuously rotated drum contactor 10 driven by motor 'Hthrough reduction gearing 12 and bevel gearing 13 connected to shaft 14of the drum. Motor 'Il is a constant speed motor of any preferred typesuitably energized by a local source of the aircraft or vessel. Drum 'l0is rotated at the rate of about two to three revolutions per second inthe preferred case, to properly actuate indicator needles I and 2 ofcomposite indicator 15 in accordance with the directional indications ofthe system, as will be described.

The radio system comprises two separate radio frequency tuning units 'I6and 11. Units 16 and 11 have individual tuning controls whereby thepilot tunes to the predetermined frequencies of the respective groundstations. A rotatable directional antenna and a non-directional antennais connected to the input of each radio frequency tuning unit.Non-directional antenna 18 and loop antenna 19 are connected to radiofrequency tuning unit 10. Loop antenna 19 is connected to unit 16through slip rings 82 and connection leads 83. Loop 8| is connected tounit 11 through slip rings 84 and connection leads 85.

A single amplier and control system 86 is employed for the receiver toconserve Weight, bulk, and cost. A local source of audio frequencycurrent 81 is used to produce the proper control signals for operatingthe loop antennae to their bearing positions. A frequency of 102.5cycles has been found satisfactory. The schematic showing of theconnection of generator 81 with units 16, 11 and 86 signifies itssuitable connection in the circuit in a manner preferably as disclosedin my United States Patent No. 2,308,521 issued January 19, 1943 and mycopending application, Serial Number 291,807, now Patent No. 2,379,362,granted June 26, 1945.

The output of radio frequency tuning units 16 and 11 is at the chosenintermediate frequency common to the system. The mechanical orelectronic switching operation of the outputs of units 16, 11 is thusperformed more eiciently than at radio frequency. The output of unit 16is connected to intermediate frequency transformer 88; the output ofunit 11, to intermediate frequency transformer 89. Unit 86 comprises anintermediate frequency amplifier, rectifier, audio frequency amplifier,and electronic or thyratron control system. The latter unit is actuatedto control the movement of the loop antennae into the bearing positions.An intermediate frequency transformer 90 connects to the input of system86. The outputs of intermediate frequency transformers 88 and 89 aresuccessively connected to the input of intermediate frequencytransformer 90 through the switching means 10.

The drum Commutator comprises a plurality of commutator segments,arranged in three groups. The first group contains 180 or semicircularsegments 9|, 92, 93. The intermediate group contains 360 or circularsegments or rings 94, 95, 96. The third group comprises 180 orsemi-circular segments 91, 98, 99. First group 9|, 92, 93 correspond toradio frequency unit 16 and associated loop antenna system 19; the thirdgroup 91, 98, 99 corresponding to radio frequency unit 11 and associatedloop antenna system 8|'.

Segments 9|, 92, 93 are mechanically displaced by 180 with respect tosegments 91, 98, 99. Only one of these two groups of segments can thusbe in electrical contacting relationship with their associated brushesin alignment as shown. Continuous rotation of drum 10 causes alternateand successive connection and disconnection of radio frequency units 16,11 and associated Commutator segments. Commutator segments 9| and 91 areelectrically connected with 360 segment or slip ring 94 through lead|00; segments 92 and 98, to ring 95 through lead I0|; and segments 93and 99, to ring 96 through lead |02.

The secondary winding of intermediate frequency transformer 88 isconnectible to semicircular segment 9| through lead |03. The secondarywinding of intermediate frequency transformez' 89 is connectible tosemi-circular segment 91 through lead |04. Only one of the two tuningunits 18, 11 is connectible to intermediate frequency transformer 90 atany given instant due to the 180 phase displacement of theircorresponding segments 9|', 91 on drum 10. The primary of intermediatefrequency transformer 90 is in continuous connection with slip ring 90through lead |05, and thus with either lead |03 Cil or lead |04 to oneof the units 16, 11. The common amplifier control system 86correspondingly serves both radio frequency tuning units 16 and 11 dueto the successive connection thereto. As indicated, head phones |06 maybe connected to system 86 for aural reception through the audiofrequency section thereof.

The control signal output of system B6, derived from the directionallyreceived signals as modified by local generator 81, is conducted to therespective loop antenna drive systems as follows: Output leads |01 ofsystem 86 connect with slip rings 95, 96 through suitable brushes.Commutator segments 92, 93, in parallel connection with rings 95, 96,-connect to motor |08 of loop antenna 19 through leads |99.Electromagnetic clutch IE6 is in parallel connection with motor |08.Motor |08 drives loop antenna 19 through gearing and loop sleeve l2.Motor I3 of the second loop antenna system 8| is connectible to segments98, 99 through leads ||4 and thence to the output of system 86.Electromagnetic clutch H5 is connected in parallel with motor H3. Motor||3 drives loop antenna 8| through clutch H5, gearing IIE, and loopshaft ||1. Loop shaft ||1 is concentric with sleeve |'2 due to thecoaxial arrangement of the loop antenna windings. A streamline housingls indicated in dotted outline about the antennae upon external mountingthereof to reduce aerodynamic resistance in flight.

Simultaneous with the connection of the output of radio frequency tuningunit 16 to amplifier control system 86, motor |08 and electromagneticclutch I|0 of antenna system 19 are placed in electrical connection Withthe control output of system 86. During this interval, corresponding tothe illustrated position of the drum 10, the other radio frequencytuning unit 11, its assoelated motor I3, and clutch l5, are disconnectedfrom system 86. When unit 16 is tuned to the inner transmitter station,motor |08 is energized by system 86 to motivate loop antenna 19 into thenull signal position or bearing relationship with the station in themanner disclosed in my Patent No. 2,308,521.

A telemetering unit is used to communicate the angular ppsition of loopantenna 19 to in needle of composite indicator 15. An electricaltelemetering arrangement is illustrated, comprising position transmitter|'|8 connected to meter 15 through electrical cable ||9, and a positiontranslator or indicator located within meter 15. My Patent No. 2,379,362describes in further detail arrangements for the telemetering andcomposite arrangement Within meter 15. The chosen interval for theswitching action of one-third to one-half of a second is ample in thepractical embodiment to bring the loop antenna into null signal orbearing relationship with the transmitter station it is tuned to.

During the next succeeding interval, loop antenna system 19 and itsassociated tuning unit 16 are disconnected from amplifier control system86. The loop antenna 19 thereupon remains stationary, as does itsbearing indication by needle. The second radio frequency tuning unit 11and its associated loop antenna system 8| including the motor drivetherefor are thereupon connected with system 86 through Commutatorsegments 91, 98, 99. Radio frequency tuning unit 11 is, in the presentcase, tuned to the carrier frequency of the second transmitter, namelythe outer ground station. The output of system 86 operates motor I3 andmagnetic clutch ||5 to drive loop antenna 8| into the null signalposition or bearing relationship with the transmitter. The position ofloop antenna 8| is communicated to out indicator needle 2 throughposition transmitter H8' and electrical cable H9 connecting to theposition translator within indicator l5.

Lateral guidance with the system of the invention is obtained in themanner described hereinabove in connection with Fig. 1 of my PatentNumber 2,379,363, using transmitter stations with different carrierfrequencies continuously radiated. The single amplifier control unit 86is disclosed as mechanically switched between the two tuning units 16and 11. The mechanical switching arrangement has been shown to simplifythe disclosure of the principle involved in this form of the invention,namely that of switching the loop systems and indicators locallycontrolled at the receiving system. It is to be understood, however,that this is exemplary only, and that other equivalent switchingarrangements either electrically, electronically or mechanicallyoperated, may be used within the scope of the invention.

While one embodiment of the invention has been shown and described indetail to illustrate the application of the principles thereof, it willbe obvious that the invention may be otherwise embodied withoutdeparting from such principles.

What is claimed is:

l. The method of radio guidance which comprises transmitting signals ofdifferent radio frequencies from a plurality of points; directionallyreceiving the diiferent radio signals separately by the manipulation ofa like plurality of antennas; successively connecting the separatelyreceived radio signals to a ycommon system for amplifying them; derivingtherefrom independent directional bearings on each of the points ofradio transmission; and continuously maintaining each of such bearings.

2. The method of laterally guiding a mobile craft with respect to apredetermined path which comprises transmitting signals of differentradio frequencies from two points spaced along the path; directionallyreceiving the different radio signals aboard the craft by themanipulation of a pair of antennas; successively and intermittentlyconnecting the received radio signals to a common system for amplifyingthem; deriving therefrom independent directional bearings on each of thepoints of radio transmission with respect to the lateral position of themobile craft; and continuously maintaining each of such bearings.

3. The method of laterally guiding an aircraft with respect to apredetermined path of approach to a runway which comprises transmittingsignals of different radio frequencies from two points spaced along thepath by a predetermined amount; directionally receiving the differentradio signals aboard the aircraft by the manipulation of a pair ofantennas; successively connecting the received radio signals forsubstantially equal intervals to a common system for amplifying them;deriving therefrom independent directional bearings on each of thetransmitted radio signals with respect to the position of the aircraft;and continuously maintaining each of such bearings.

4. The method of laterally guiding an aircraft with respect to apredetermined path of approach to a runway which comprises transmittingsignals of different radio frequencies from two points spaced along thepath by a predetermined amount; directionally receiving the differentradio signals aboard the aircraft by the manipulation of a'pair ofantennas; successively connecting the received radio signals forsubstantially equal intervals to a common system for amplifying them;deriving therefrom independent directional bearings on each of thetransmitted radio signals with respect to the position of the aircraft;and maintaining the directional bearings constant between such intervalsof connection of the received radio signals to the common system foramplifying them.

5. A radio directional receiving system comprising a plurality ofrotatable directional antennae having individual motive drives; a radiofrequency receiver unit connected to each of said antennae; an amplifierand control system connectible to the output of each of said receiverunits; and switching means for successively connecting the output ofeach receiver unit to the input of said amplifier and control systemwhile correspondingly connecting the output thereof to the respectivemotive drives to orientate their associated rotatable antennae intodirectional bearing relationship with radio signals received by saidreceiver units.

6. A radio directional receiving system comprising two rotatabledirectional antennae having individual reversible motor drives; a radiofrequency receiver unit connected to each of said antennae; an amplifierand control system connectible to the output of each of said receiverunits; switching means for successively and intermittently connectingthe output of each receiver unit to the input of said amplifier andcontrol system while correspondingly connecting the output thereof tosaid reversible motor drives to orientate their associated rotatableantennae into directional bearing relationship with received radiosignals; and an indicator coupled with each of said rotatable antennaeto indicate their bearing positions.

7. A radio directional receiving system comprising two rotatabledirectional antennae having individual reversible motor drives; a radiofrequency receiver unit connected to each of said antennae; an amplifierand control system connectible to the output of each of said receiverunits; electro-mechanical switching means for successively andintermittently connecting the output of each receiver unit to the inputof said amplifier and control system while correspondingly connectingthe output thereof to said reversible motor drives to orientate theirassociated rotatable antennae into directional bearing relationship withreceived radio signals; and an indicator coupled with each of saidrotatable antennae to indicate their bearing positions.

8. A radio directional receiving system comprising two rotatabledirectional antennae having individual reversible motor drives; a radiofrequency receiver unit connected to each of said antennae; an amplifierand control system connectible to the output of each of said receiverunits; switching means for successively and intermittently connectingthe output of each receiver unit to the input of said amplier andcontrol system while correspondingly connecting the output thereof tosaid reversible motor drives to orientate their associated rotatableantennae into directional bearing relationship with radio signalsreceived by said receiver units; a pair of antenna position indicators;and a telemetering arrange" ment connecting each indicator to one ofsaid tion thereof.

f directional yantennae to indicate the bearing posis. A radiodirectional receiving system` coml plising ka plurality of rotatabledirectio-nal anrespective motive rdrives to orientate. their associatedrotatable antennae'intofdii'ectional bearing relationship withradiosignals'received by for rotating said drum at a substantiallyconstant speed.

.12. A radio' directional receivingsystem rcomprising a pair ofconcentrically mounted .rotatable directional antennae mounted in acommon housing andhaving lindividual reversible motory drives; a radiofrequency lreceiverfunit connected rt the rwinding of each ofl saidantennae; an .amplierand control system connectible to the output ofeach'of said receiver units; synchronous switching means forsuccessively and intersaid receiver units; said switching meanscomprising a drum contactor having two diametrically oppositely disposedsets ofdiscontinuous contact segments, brush means for connecting eachof said sets to one of said antennae'andone of said reversible motordrives, asetof continuouscontact segments connected to each set ofdiscontinuous contact segmentsand brush means connecting the last-namedsettothe input and outf put oisaid amplifier and. lcontrol system; and

mechanism yforr rotating said drum at a suicstantially constantl speed.l.

"10. A radio directional `receiving system com-r prising a pair ofyconcentrically mounted rotatable directional antennae mounted inacommon Ahous-r ing and having individual reversible motor drives;

, aradio frequency receiver unit connected to the winding of each ofsaid antennae; an yamplifier and control system connectible to theoutput of yeach. yof said receiver units; synchronous switching. meansfor successively and intermittentlyl connecting the. -outputof each.receiver unitl to` the input of said amplifier and control system whilecorrespondingly. connecting theA output thereof to said reversiblemotordrives to orientate their associated rotatable antennae into directionalbearing relationship With radio signals received by said receiver units;and a pair of coaxial antenna position indicating pointers each coupledto one of said antennae to indicate the bearing position thereof.

11. A radio directional receiving system comprising a pair ofconcentrically mounted rotatable directional antennae mounted in acommon housing and having individual reversible motor drives; a radiofrequency receiver unit connected to the winding of each of saidantennae; an amplifier and control system connectible to the output ofeach of said receiver units; synchronous switching means forsuccessively and intermittently connecting the output of each receiverunit to the input of said amplifier and control system whilecorrespondingly connecting the output thereof to said reversible motordrives to orientate their associated rotatable antennae into directionalbearing relationship with radio signals received by said receiver units;and a pair of coaxial antenna position indicating pointers each coupledto one of said antennae to indicate the bearing position thereof; saidswitching means comprising a drum contactor having two cliametricallyoppositely disposed sets of discontinuous contact segments, brush meansfor connecting each of said sets to one of said antennae and one of saidreversible motor drives a set of continuous contact segments connectedto each set of discontinuous contact segments and to the input and ouputof said amplifier and control system and mechanism including a constantspeed motor mittently connecting the output of yeach receiver unit tothe input of said amplifier and; control system while correspondinglyconnecting the output thereof to said reversible motor drives toorientate. their .associated rotatable antennae into directional bearingrelationshipwitli radio signals; receivedfby said receiver units; a pairindicate the bearing position thereof. l 13. A direction finder systemcomprising ai lpair rof Adirectional receiving circuits, one beingtunable'to the'carrier frequency of one station,

l l of another station; a pair'of utilization circuits,y

of coaxial antenna position indicating pointers;

and a telemetering arrangement connecting eachpointerltoone ioisaiddirectional antennae the other being tunable to the carrierfrequencycommon amplifier and detector means coupling said utilization circuitsto said directional receiving circuits, and means for causing both saiddirectional. receiving. circuits and saidutilization lcircuits to bealternately `operative at. a l

similar periodicity whereby eachr of said utilization circuits will beresponsive in accordance with f f the 'output` of only one of saiddirectional i'el l .ceiving circuits.

A14. A direction riinder f systemr comprising a pair of directionalreceiving circuits, one being tunable tothe carrier vfrequency of onestation,

the other being tunable to the carrier frequency of another station,means for alternately suppressing the output of each of said directionalreceiving circuit which is time displaced from the correspondinglyinterrupted output of the other directional receiving circuit, commonmeans for amplifying said time displaced outputs, and means forsubsequently utilizing such amplied outputs in the guiding of a vehiclealong a predetermined course.

l5. A direction iirider system comprising a pair of directionalreceiving circuits, one being tunable to the carrier frequency of onestation, the other being tunable to the carrier frequency of anotherstation, means for alternately suppressing the output of each of saiddirectional receiving circuits to produce an interrupted output of onedirectional receiving circuit which is time displaced from thecorrespondingly interrupted output of the other directional receivingcircuit, common means for amplifying and detecting said time displacedoutputs, a pair of branch utilization circuits coupled to said commonamplifying and detecting means, and means for alternately rendering saidbranch circuits responsive to the output of said common amplitying anddetecting means at the same rate as the alternate suppression of saiddirectional receiving circuits, whereby each of said branch utilizationcircuits is caused to respond in accordance with the output of one ofsaid directional receiving circuits.

16. A direction finding system comprising a pair of directionalreceiving circuits, one being tunable to the carrier frequency oftransmission of one station, the other being tunable to the andavocarrier frequency of another station, amplifying means common to saidpair of directional receiving circuits and adapted to amplify the outputfrom each of said directional receiving circuits, a pair of utilizationcircuits coupled to said common amplifying means and adapted to functionin accordance with signal variations in the output of said directionalreceiving circuits, means for periodically and alternately suppressingthe signal output from said directional receiving circuits to saidcommon amplier means, and means for periodically and alternatelyrendering said utilization circuits responsive to signal energy fromsaid common amplifier means and at the same periodicity as thesuppression of the receiving circuit output to said common amplifyingmeans whereby each utilil0 zation circuit can be made to respondexclusively to the signal variations of but one of said pair ofdirectional receiving circuits.

WILLIAM P. LEAR.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS

